What spinoff characters have reverted? The only character I can think of who'd even vaguely fit that qualifier is Submariner, except the only reason he reverted was because he was licensed out separately in the first place ( to Universal ).

I would prefer they avoid doing an alien invasion scenario for the next film. The Avengers handled it fine, and it would be nice to see alternative threats to the world (Masters of Evil, Galactus, Ultron...)

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"Johnny Storm's a good-hearted kid, sure, but he has the attention span of a toaster, and he leads with his face; in Johnny's undisciplined mind, there's only a single synapse between thinking and doing. The Avengers' battle cry is "Avengers Assemble"; the Fantastic Four's is "Johnny, WAIT!"----Mark Waid

“We have a number of candidates from the comics and from the movies we’ve already made. It’s just a matter of finding the right storyline, the right filmmaker, the right time.” Someone in the audience yelled “She-Hulk!” Feige responded, “She-Hulk would be pretty great.”

So it seems that it's more based on the script and when they find someone with the right vision, and less about whether it fits into the Phase.

I don't think Ant-Man specifically "fits into what they're doing" for Phase Three--they were just waiting on when both the script and Edgar Wright were ready before they could start production. I honestly believe that if they had been in position to release it in November 2014 (and therefore have it be Phase Two, they would have, and it would have had nothing to do with whether it "fits into what they're doing" with the Phase.

All that said, I'd totally be game for a female solo superhero movie that doesn't suck. I've been waiting for one for some time now!

what i'd like to see for phase 3 is -
daredevil
Captain America 3 - The Invaders
doctor strange
black panther
(i'd love to see a captain Britain but don't think i'll ever see one on the big screen)
The New Avengers

We know Ant-Man, Strange, sequels to Cap and Thor are sure fires. Feige has continued to hint at Inhumans. A sequel to GotG if the first does well is a good assumption. BP has recently been hinted at as coming. And with Feige stating they're looking into females characters there's a chance there could be one in Phase 3.
I think Marvel understands they can't make it an all boys club forever and 2 phases is long enough.

With Whedon basically confirming Thanos for Avengers 3; I think they have to end the current storyline: Phases 1-3 with a MASSIVE 3 part Infinity Gauntlet series. Why not take Marvel's most epic crossover story and bring it to the big screen?

This way the Infinity Gauntlet trilogy could conceivably feature ALL of the characters and be the biggest trilogy of all time. This would be an amazing end to The Avengers arc. That would total a 19 film interconnected cinematic universe. That's pretty amazing and revolutionary! The MCU could still continue on but with new actors and storylines.

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The Avengers..The New Avengers
The Guardians of the Galaxy..The DefendersVS.ThanosMARVEL'S THE INFINITY WAR

FANTASTIC FOUR"This is our chance to make a difference" - Sue Storm - The Invisible Woman"He's stronger than any of us but he's not stronger than all of us" - Reed Richards - Mr. Fantastic"We could these powers to help people" - Johnny Storm - The Human Torch"You can't fix this, nobody can" - Ben Grimm - The Thing